Compact HMSIW four-way filtering power divider with pre-defined division ratio

A novel and simple design approach of compact four-way filtering power divider (FPD) using half-mode substrate integrated waveguide (HMSIW) cavity is investigated in this letter. The pre-defined power division ratio of the four outputs is obtained by adjusting the external quality factor (Q(e)) of each output port, while the total output Q(e) is equal to the input Q(e). The four outputs are loaded to a single HMSIW resonator, achieving a compact size. Meanwhile, both bandpass response and power division can be designed independently. For demonstration, a prototype with pre-defined power division ratio of 1:3:3:1 is designed, fabricated, and measured. The measured results show that the FPD centered at 4.88 GHz owns a 3-dB fractional bandwidth (FBW) of 11.3%. The insertion loss of the passband is about 1.4 dB and the return loss is better than 17 dB, meanwhile the phase differences of in-phase four outputs are all within 5 degrees from 4.61 to 5.16 GHz. Good agreement is observed between the simulated and measured results.